package com.yan.demo;

import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class Demo4 {
    public static void main(String[] args) {
        System.out.println(System.nanoTime());
        //System.exit(0);
        System.out.println(Math.ceil(3.14));
        System.out.println(Math.floor(3.14));
        System.out.println(Math.max(1.14, 5.26));
        Properties properties = System.getProperties();
        Set<Object> keys = properties.keySet();
        for (Object key : keys) {
            Object value = properties.get(key);
            System.out.println(key + "---------" + value);
        }
        Map<String, String> map = System.getenv();
        Set<String> strings = map.keySet();
        for (String string : strings) {
            String s = map.get(string);
            System.out.println(string+"-----------" +s);
        }
    }
}
